THE A34 northbound carriageway will not reopen until 10pm tonight (Thurs) the Highways Agency has warned.
The road is currently closed from East Ilsley to the Chilton Interchange due to an overturned car transporter, with delays of around an hour being reported.
Only one lane is running on the southbound carriageway due to the incident.
Police have told motorists to expect significant delays and to find alternative routes wherever possible.
Traffic for the A34 north is advised to remain on the M4 westbound to J14, then follow the Black Diamond symbol signed diversion route, to rejoin the A34 at the A4130 (Milton Interchange).